A lithium-ion secondary battery includes therein a positive electrode and a negative electrode which are separated by a porous separator. In production of lithium-ion secondary batteries, a separator roll is used which is obtained by winding this separator around a core having a cylindrical shape.
In production of lithium-ion secondary batteries, intrusion of dust is fatal, and therefore the separator roll is packaged such that dust would not intrude and waste which becomes dust would not be generated. Moreover, in order to enhance efficiency in transportation and packaging, one (1) core member is inserted into a plurality of separator rolls, and these components are assembled into one (1) roll assembly.
For example, in a configuration disclosed in Patent Literature 1, an inner core having a cylindrical shape is passed through a plurality of rolls, protection sheets for protecting end surfaces of the plurality of rolls, and spacers each of which is provided between adjacent two of the plurality of rolls, and those components are packaged with a packaging film. Patent Literatures 2 and 3 disclose other members which are directly engaged with shaft holes of cores in rolls so as to protect end surfaces of the rolls, as with the protection sheets.
Moreover, for example, in a configuration disclosed in Patent Literature 4, a branch pole section which protrudes from a plate-like section in a lateral direction is passed through cores of a plurality of rolls, and a buffering material is screwed to an end surface of the branch pole section so as to prevent the rolls from falling off from the branch pole section.